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SM465 gas mileage is gonna BLOW!

Discussion in 'The Garage' started by Ben B., Nov 5, 2006.

  1. Ben B.

    Ben B. 1/2 ton status

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    Been driving my new K10 w/ 350 and 465 around town last couple days.

    The problem lies with 3rd gear.

    At low rpms it's way too weak in 3rd, so I have to downshift to 2nd and be at like 3500rpms to get up a hill or whatever on the road.

    Then at like..55-65? [My speedo likes to fly around randomly]
    It runs like 2000-2500rpms.

    I'm thinking I'd be MUCH better off with a 700R4..but whatever.
     
  2. bowtiepower00

    bowtiepower00 1/2 ton status

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    Something's not right then. What gearing and tires do you have? My truck will run in 3rd from 10mph, no problem. Are you sure the engine is running right?
     
  3. MattK

    MattK 1/2 ton status

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    what size tires? gears? and what kinda hills are you talkin about?

    im running 4.56's and 37's...the only time i need to downshift is while turning and whatnot.
     
  4. ryan22re

    ryan22re 1/2 ton status

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    x2 my 85 has 2.73's (ugh) and I can run around in 3rd to 15-20 mph.

    Gonna switch to 3.73's or 3.42's eventually which would make it even better. You sure its a 465? Could be that goofy 3 speed w/ overdrive.
     
  5. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    my cousin almost bought a pos with 2.73s and 33s with a 465, what a pig..
     
  6. Ben B.

    Ben B. 1/2 ton status

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    It's all stock. Stock size tires, not sure on gear ratio.

    Yes it's a 465.

    I'm sure it COULD run around in 3rd at 15mph...But i'm talking about an actual driving situation where you have to get somewhere actually moving at speed.

    It's got plenty of balls in 1st and 2nd, but as soon as i put it in 3rd it's a total turd.

    EDIT: and engine runs great.
     
  7. pvfjr

    pvfjr 1/2 ton status

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    I'd worry about your motor then. I had 3.73's, 36's, and an OLD and very WORN out 350 with ignition and carb problems, and I daily drove it and never had a problem. 3rd gear worked great at any speed above 25-30, and yes, that's with speed and actually wanting to get somewhere in a real driving situation. My truck was much more lively with the 465 than with the th350 it had before it. You could feel a significant difference when it didn't have the slush box bogging it down.
     
  8. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    my old 86 had a 350/465/208 and that 465 was AWESOME... never even used the low gear unless i wanted to crawl or drag something...33s with 3.42s and i think i MAY have gotten 6-10 mpg, but the 350 was ragged, and i was 16...
     
  9. bowtiepower00

    bowtiepower00 1/2 ton status

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    I can put my truck in 3rd at 10mph and accelerate away from a stoplight faster than the traffic around me. That is without opening the secondaries on my q-jet. At 65-70mph on my speedo, I run about 3K on the tach with 31's. Once I get to 3rd, I leave it there unless I am coming to a complete stop.
     
  10. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    I'm not quite sure where to start looking on this one but I realy like my K20 with a 465. 38's and 4.10 and you can pretty much run 3rd gear for any situation. I think it has a 350 in it. I haven't had the truck very long and never bothered to verify what motor is in it, might be a 327.
     
  11. Ben B.

    Ben B. 1/2 ton status

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    Well then I wonder what the problem is?

    Motor runs fine, doesn't smoke...gets around 50psi oil pressure at idle...Never had any incident where it ran bad.

    It's just really sluggish in 3rd?? The truck seemingly has no low end power.

    I'm clueless
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    You need to find out what gears you have. I bought my '81 Jimmy 10 years ago and was surprised I needed to use granny low to get going before i could shift into second and carry on. Seemed pretty gutless too...

    Fourth gear was basically highway only.

    Truck had 2.73's and 33's. :doah: :doah: :doah:

    I think it would have been only slightly less stupid with stock tires on it. With 3.73's later it was a ton better.

    Rene
     
  13. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Well first I think people need to clear up some misconceptions...

    Such as I think some of us are talking about 2 different patterns:
    L-1-2-3 or 1-2-3-4


    From the sound of it, your engine is either gutless or your geraing sucks.

    I can hold my 305 just off idle and accelerate enough to shift a few times to get all the way to 4th and never go above 1500rpm. Also I learned how to drive stick on this tranny so its just 2nd nature for me. :D

    At 65mph I'm turning at 2800ish rpm with 4.10s and 35" tires.
     
  14. pvfjr

    pvfjr 1/2 ton status

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    Well I think everyone talking about using 3rd at nearly all speeds are talkin L-1-2-3, so that's that way I referenced it in my input as well.
     
  15. MattK

    MattK 1/2 ton status

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    yeah i call the last gear 3rd as well. low, granny, first forward gear, etc is too low to really be of any use on the street. IMO
     
  16. blazin_blazer

    blazin_blazer 1/2 ton status

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    i had a truck on a blazer frame that had the 350/465/205,the 350 had the holley systemax treatment(aluminum heads, intake, carb, and camshaft, and timing chain) and the cast 11to1 pistons from P.A.W. (thats with 64cc heads, i had 76cc so it was closer to 10 to 1) the systemax literature said 410 hp with stock short block with my bumped compression i'll call it 425 hp.

    i had 3/4 ton axels with 3.42:1 ratio and super swamper 38x12.50x15. around town it was a gasaholic,(lead foot) but i had to make afew long trips in it and with my gears so tall and tires that tall and such a stout motor on the hiway at 60 i was running about 1100-1200 rpm. i checked the gas consumption in my rig and drove the very same route the next day in a bone stock toyota to get the mileage. i did the math and i thought i did something wrong.

    so i did it again, 2 hrs on the road can't remember the miles anymore, but it came out the same.....21mpg...in a mudder....and i had a ceramic brass clutch in it (water get on it the harder it bites, kinda like oil on a drill bit it washed away the powder and made it grab!!!)and once i figured out that there was no slipping that clutch wet or dry,it was either engaged or disengaged, i drove it around town with 2 gears 2nd and 3rd using the L-1-2-3 pattern i took off in second and shifted it once, staight back into third from one light to the next. i loved it, really don't know why i sold it, thats my one ride i wish i still had.

    put transfer in 4lo and tranny in 1st, i had all the gear i ever needed, if not i'd go to granny lo, i had it then, but usually used 1st, occasionally 2nd when i needed to blurp the throttle to clean out my tires, i shure miss that truck, i'm going to build me another just like it and make arrangements to be buried in it!!!
     
  17. Ben B.

    Ben B. 1/2 ton status

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    Bump.
     
  18. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    does someone just want to be the top thread or what? read the replies and take the advice... do a tune up, check your compression, check your gears... do it, then come back
     
  19. Ben B.

    Ben B. 1/2 ton status

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    Why on earth would I care about being the top thread?

    I have 130 posts here after over a year...Do I look like a post whore to you? Please.


    Just trying to get more opinions.
     
  20. stizkidz

    stizkidz 1/2 ton status

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    'm not gonna lie - I didn't read through the whole thread. But, I have a 350/465 combo K5. I run 35"s and 4.10s. It's a doggg and gas mileage is pathetic. I pretty much only drive in 3rd/4th (pretend its a Powerglide). 1st for pulling down a brick wall, 2nd for pulling away from a light, 3rd for cruising, 4th for highway. The gear spacing sucks, plain and simple, you just gotta deal with it...
     

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